pythonPackages.osqp: remove mkl
pythonPackages.osqp: remove mkl

Also add scipy.
Cleanup commit slightly for formatting.
Removing mkl allows this to be built in Hydra (mkl = unfree),
and it seems the mkl dependency is somewhat optional given downstream
packages build cleanly when removing mkl.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs